User interfaces are systems by which people interact with machines to operate and control the machines and receive feedback from the machines. Typically, to interface to an electronic system, a user interface includes hardware and software components. Different types of user interfaces include graphical user interfaces that accept input via devices such as a computer keyboard and mouse, web-based user interfaces that accept input and provide output by generating web pages, and touch panels or touchscreens that display information and accept input by the touch of a finger or stylus.